This invention relates to a fluid applicator which is filled with a highly viscous fluid such as correction fluid or make-up fluid.
In an applicator having a spherical application member (applicator ball), a tip is attached to the neck formed at the front end of a fluid tank which is filled with a fluid to be applied, and the tip rotatably supports therein an applicator ball in such a way that the applicator ball may partly be exposed from the front edge thereof like in a ball-point pen. The applicator ball is resiliently urged by a spring so as to bring the applicator ball into intimate contact with an inwardly tapered front edge of the tip, when the applicator is not used, to allow the applicator ball and the front edge of the tip to form a valve, preventing the fluid from being discharged.
When the applicator ball is pressed against a surface to be treated by application of the fluid, the applicator ball retracts against the resilience of the spring to provide a clearance between the applicator ball and the front edge of the tip, allowing the fluid behind the applicator ball within the tip to be delivered through the clearance to the outside of the tip and applied as the applicator ball rolls. However, since the fluid is highly viscous, the fluid cannot normally be fed freely to the surface of the applicator ball. Accordingly, the fluid tank is molded by means of blowing using a flexible material so as to be squeezable, and the fluid tank is pressed between the user's fingers to increase the internal pressure of the fluid tank when the applicator is used to allow the fluid to be fed out to the exposed surface of the applicator ball with the aid of the thus increased pressure.
Thus, the prior art applicator suffers from the disadvantage that the handling thereof is troublesome since the fluid tank must be pressed between the fingers to increase the internal pressure when the fluid is to be applied, and besides the production cost of a fluid tank blow-molded from flexible material is relatively high.
Therefore, if a cap is designed to be push-fitted to the neck of the applicator with the front end portion of the tip being sealed inner barrel of the cap to reduce the volume of the sealed space defined within the inner barrel in the process that the cap being engaged with the neck, the internal pressure of the inner barrel can be increased. Accordingly, the application ball retracts to allow the air in the inner barrel to intrude into the fluid tank and increase the internal pressure of the fluid tank, and thus the fluid tank need not be pressed between the fingers for application of the fluid.
However, since the internal pressure of the fluid tank is increased each time the cap is fitted in such cap pressurizing system, the internal pressure of the fluid tank becomes too high, and it sometimes happens that the fluid to be applied is discharged excessively when the applicator is used.